package com.intexh.quickandroid.module.chat.sprinkles;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v4.content.AsyncTaskLoader;


class SupportCursorLoader extends AsyncTaskLoader<Cursor> {

    private final ForceLoadContentObserver mObserver;

    private String mSql;
    private Class<? extends Model>[] mDependencies;
    private Cursor mCursor;

    public SupportCursorLoader(Context context, String sql,
                               Class<? extends Model>[] dependencies) {
        super(context);
        mObserver = new ForceLoadContentObserver();
        mSql = sql;
        mDependencies = dependencies;
    }

    /* Runs on a worker thread */
    @Override
    public Cursor loadInBackground() {
        final SQLiteDatabase db = DbOpenHelper.getInstance();
        Cursor cursor = db.rawQuery(mSql, null);

        if (cursor != null) {
            // Ensure the cursor window is filled
            cursor.getCount();

            if (mDependencies != null) {
                cursor.registerContentObserver(mObserver);
                for (Class<? extends Model> dependency : mDependencies) {
                    getContext().getContentResolver().registerContentObserver(
                            Utils.getNotificationUri(dependency), false, mObserver);
                }
            }
        }
        return cursor;
    }

    /* Runs on the UI thread */
    @Override
    public void deliverResult(Cursor cursor) {
        if (isReset()) {
            // An async query came in while the loader is stopped
            if (cursor != null) {
                cursor.close();
            }
            return;
        }
        Cursor oldCursor = mCursor;
        mCursor = cursor;

        if (isStarted()) {
            super.deliverResult(cursor);
        }

        if (oldCursor != null && oldCursor != cursor && !oldCursor.isClosed()) {
            oldCursor.close();
        }
    }

    /**
     * Starts an asynchronous load of the contacts list data. When the result is
     * ready the callbacks will be called on the UI thread. If a previous load
     * has been completed and is still valid the result may be passed to the
     * callbacks immediately.
     * <p/>
     * Must be called from the UI thread
     */
    @Override
    protected void onStartLoading() {
        if (mCursor != null) {
            deliverResult(mCursor);
        }
        if (takeContentChanged() || mCursor == null) {
            forceLoad();
        }
    }

    /**
     * Must be called from the UI thread
     */
    @Override
    protected void onStopLoading() {
        // Attempt to cancel the current load task if possible.
        cancelLoad();
    }

    @Override
    public void onCanceled(Cursor cursor) {
        if (cursor != null && !cursor.isClosed()) {
            cursor.close();
        }
    }

    @Override
    protected void onAbandon() {
        super.onAbandon();
        getContext().getContentResolver().unregisterContentObserver(mObserver);
    }

    @Override
    protected void onReset() {
        super.onReset();

        // Ensure the loader is stopped
        onStopLoading();

        if (mCursor != null && !mCursor.isClosed()) {
            mCursor.close();
        }
        mCursor = null;
    }

}
